Which of the following is not the physiological effect of Ethylene ?

Options

A. Increasing absorption surface of root
B. Elongation of apple fruits
C. Enhances rate of respiration during fruit ripening
D. Petiole elongation in deep water rice plants

Answer

To determine which of the following is not a physiological effect of ethylene, we will analyze each option provided in the question.

1. **Increasing absorption surface of roots**: Ethylene is known to inhibit the growth of main roots and promote the growth of root hairs. This results in an increased surface area for absorption. Therefore, this statement is true and is a physiological effect of ethylene.

2. **Elongation of apple fruits**: Ethylene is primarily involved in the ripening of fruits rather than their elongation. While ethylene does play a role in fruit development, it does not specifically cause the elongation of apple fruits. Instead, it is more accurate to say that ethylene promotes the ripening process. Thus, this statement is not a physiological effect of ethylene.

3. **Enhances the rate of respiration during fruit ripening**: Ethylene is known to enhance the rate of respiration during the ripening of fruits. This phenomenon is referred to as a climacteric rise in respiration. Therefore, this statement is true and is a physiological effect of ethylene.

4. **Petiole elongation in deep water rice plants**: Ethylene promotes rapid elongation of the petiole in deep water rice plants, allowing them to grow taller to reach the water surface. This is indeed a physiological effect of ethylene.

Based on the analysis, the option that is not a physiological effect of ethylene is the **elongation of apple fruits**.

### Final Answer:
The option that is not a physiological effect of ethylene is: **Elongation of apple fruits**.

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